A source close to Attkisson confirmed her helpless feelings, saying she was annoyed with being kept off "The CBS Evening News."

"It’s no secret that Sharyl has been unhappy about CBS' lack of interest in investigative reporting, especially when it comes to stories about the Obama administration," the source told Politico.

CBS issued its own statement Monday following Attkisson's departure.

"CBS News veteran Sharyl Attkisson is leaving the news division to pursue other endeavors," Sonya McNair, senior vice president for communications for CBS News, said in a statement. "We appreciate her many contributions and we wish her well."